Bearings are used to guide structural parts movably with respect to each other, for example, by two bearing rings arranged concentrically about each other, one of which is arranged in a rotationally fixed manner, with the rings rolling directly or indirectly against each other. Depending on the size and construction of the bearing, substantial forces may be absorbed. Since such bearings are often installed in hard-to-reach locations, it is desirable to identify the need for servicing of the bearing well in advance, for example on account of wear, in order to keep the down time for the bearing due to servicing as short as possible. Wear usually involves an abrasion of material or damage such as cracks or chipping, especially at the surfaces absorbing the forces.
It is known, for example from EP 0922 870 A1, to install a contact pin in a bore of a bearing ring, the contact pin protruding with a certain play, such as a tenth of a millimeter, in a groove of the oppositely situated bearing ring. If the wear is large enough that the oppositely situated bearing ring touches the contact pin, the pin relays a signal indicating a need for servicing to a corresponding device. The drawback here is that the known solution can only qualitatively recognize a need for servicing, i.e., whether or not wear is present, but does not allow for any quantitative wear measurement.
Furthermore, it is known, for example from the publications WO 2008/135 123 A1, EP 529 354 B1 and DE 10 2007 020 940 B3, to provide high-frequency coils on a cage of a rolling bearing, whereby the coils induce eddy currents in a surface of a bearing ring situated opposite the cage. By measuring the eddy current density, it is possible to ascertain the radial distance from the surface and thus perform a measurement of the load or the wear in the radial direction. The drawback here is that only a radial change in distance is detected. A loading or a wear in the axial direction cannot be identified with these systems.
Finally, it is known from WO 2014/090 347 A1 to provide at least one sensor taking measurements in a noncontact manner opposite a non-steplike contour of a bearing ring. The sensor may be an inductive sensor, a capacitive sensor, an ultrasound sensor or an eddy current sensor. Thanks to the non-steplike contour, such as a ramp or a V-shaped contour, an axial displacement can also be detected. The drawback here, however, is that the radial and the axial components in the event of a combination of radial and axial displacement caused by wear or a loading situation cannot be clearly separated from each other, since in both cases the sensor or the sensors detect a change in distance along the non-steplike contour. In each instance, the contour must be fabricated extremely exactly and the bearing, or at least the sensor, must be adjusted very exactly in relation to the non-steplike contour, requiring substantial labor expense.
Thus a need exists for a bearing with sensors having a simple and compact construction and making possible a comprehensive monitoring of wear, in particular a quantitative measurement of wear, as well as a measuring of load during the ongoing operation. Likewise, a corresponding method is needed to provide for monitoring wear and/or measuring a load.